【Fiberglass free】 Once, we had used fiberglass; Long long ago, we haven't been using fiberglass any more. You and your family's health is our primary concern and protection. 【MATERIAL & CONSTRUCTION】: Iyee Nature 12 inch king firm mattress gel memory foam mattress is designed with three layers all-foam system, including 2.5" gel memory foam, 2" of High hardness confortable layer,7.5" high density base support foam for ultimate comfort. 【COMFORTABLE & BREATHABLE】: Iyee Nature king size mattress All-foam bed design combined expertise and the best materials with advanced sleep technology. Memory foam conducive to continuous airflow & breathable; skin-friendly fabrics adapt to the environment to keep the mattress surface at the ideal sleeping temperature; Buoyant, no-sink support foams adapt and conform to your body for optimal pressure relief; Specialized foams reduce motion transfer of a partner so your sleep is undisturbed.